Add error/catch boundaries in Remix to deal with server-side errors

[humphd]

We have a bunch of places in the UI's server code where we throw an error or response. These are mostly "should never happen" type situations, but as we all know, stuff happens!

Remix provides a mechanism for the front-end to deal with these error cases and show components instead of just crashing the app:

• Error Boundary - for dealing with unforeseen errors
• Catch Boundary - for dealing with error responses we throw

There are lots of good blog posts about this, like this one.

Let's start by finding all of the errors we need to deal with, and then we can split up the work of creating UI to show the user when things happen.

cc @Eakam1007, @Ririio, @Myrfion

[humphd]

The 409 we return from app/routes/__index/dns-records/index.tsx is a good example of where we need error UI.

[humphd]

There are some basic UI templates we could use for this at https://chakra-templates.dev/components/result